1. Field of the Invention
The invention relates generally to medical devices. More specifically, the invention relates to an intrauterine device and method for use.
2. Description of the Related Art
Intrauterine devices (IUDs) are a commonly used form of contraception. Generally, IUDs are believed to work by producing a spermicidal environment in the uterus and thus preventing fertilization of the egg by sperm. They may also have a post-fertilization effect, but IUDs are generally believed to produce all their contraceptive effects before implantation. In other words, IUDs are not believed to act as an abortifacient. They also typically do not affect ovulation.
There are two basic types of currently available IUDs. The copper IUD is a T-shaped device made of polyethylene wrapped with copper wire. The device acts as a foreign body within the uterus and releases copper to produce a chemical effect on the endometrium of the uterus and to alter the production of cervical mucus, thus producing a spermicidal environment. The copper IUD is approved by the FDA for ten years of continuous use.
Levonorgestrel (or “progesterone-releasing”) IUDs are also T-shaped devices and include a sleeve containing levonorgestrel, which is released into the uterus over time. The levonorgestrel adds to the foreign body effects to create added spermicidal action and also thickens cervical mucus to act as a barrier to sperm penetration into the uterus. Levonorgestrel IUDs are approved by the FDA for five years of continuous use.
Although both copper and progestin-releasing IUDs work well for contraception, both have common side effects. The most common side effects with copper IUDs are abnormal bleeding and pain. The most common side effects with levonorgestrel IUDs are hormone-related effects, such as headaches, nausea, breast tenderness, depression and cyst formation. Although complications with IUDs are uncommon, there are cases of expulsion of the IUD from the uterus and failure of the device to work, either of which may result in unwanted pregnancy. Other possible complications are perforation of the uterine wall by the IUD or intrauterine infection.
Another type of implantable contraceptive device is designed for blocking the fallopian tubes to prevent conception. One example of such a device is the Essure® permanent birth control device, manufactured by Conceptus, Inc., Mountain View, Calif. (www.essure.com). The main drawback of fallopian tube blocking implants, however, is that they are typically permanent. These devices generally promote tissue in-growth (growth of tissue in/around the implant), which permanently attaches the implant to the fallopian tube wall. This works well for permanent contraception but makes removal of such devices difficult or even impossible. Another potential drawback of such devices is that they may be more difficult to place than IUDs that simply remain in the uterus. The openings to the fallopian tubes are small and located near the top of the uterus, so placing blocking implants into the fallopian tubes may be more challenging than simply placing a device in the uterus.
Therefore, although existing IUDs work relatively well for their purpose of contraception, there is still a need for improved IUDs. Ideally, such improved IUDs would be long-acting, have relatively few, minor side effects and potential complications, and be easy to deliver and remove. At least some of these objectives are met by the embodiments described in this application.